Location Tracking and Digital Data: Can Carpenter Build a Stable Privacy Doctrine?

In Carpenter v United States, the Supreme Court struggled to modernize twentieth-century search and seizure precedents for the “Cyber Age.” Twice previously this decade the Court had tweaked Fourth Amendment doctrine to keep pace with advancing technology, requiring a search warrant before the government can either peruse the contents of a cell phone seized incident to arrest or use a GPS tracker to follow a car’s long-term movements. This time, the Court asked what the Fourth Amendment requires when law enforcement seeks cell phone records revealing the user’s approximate location when his cell phone connects to local cell towers. The Court’s answer “is a familiar one—get a warrant.” Familiar, yes; but easy, no: the Court split 5–4 with four separate dissenting opinions spanning 115 pages. The case reflects a fundamental clash between long-standing doctrinal approaches and new surveillance and digital information technologies. The government today has unprecedentedly sophisticated ways of seeing, hearing, and tracking people, ways that were unimaginable to the Fourth Amendment’s Framers. The question is whether and how the Court should adjust constitutional doctrines to maintain some historical or reasonable equilibrium between privacy and law enforcement, or whether legislatures should be the guardians of privacy in the face of technological innovation